Again a low number of otters in Naliboki Forest

Co-author Irina Rotenko

As it was reported in this blog before after the quite long period of the described more or less stability in otters in Naliboki Forest the otter population has suddenly declined manyfold by autumn 2008. For instance, during the winter 2005-2006 in Naliboki Forest on an area of 2750 square kilometers about 580 otters lived. In December 2008 during the inspection of approximately 60-70% of the habitats only 8 otters were registered. Otter survey that was gradually undertaken in other areas in Belarus in 2009-2010 evidenced that the otter population was crashed countrywide. The fast decrease in numbers and findings of dead otters suggested an epidemic in the population.

Since 2011 we noticed that the otter population started to recover in Naliboki Forest, and in 2014 it reached about 30-50% of its former population number. For instance, along the Vol’ka small river the otter population density varied between one and 2 per 10 km of the river stretch, while in the Biarezina valley it was about 2-4 otters per 10 km of the river stretch. In the summer and early autumn of 2015 fairly dense population of otters in Naliboki Forest was registered countrywide. However, in November-December 2015 the otter population declined rapidly again. In the spring of 2016 there were not more than 40 otters (more likely to say 30-35 inds) in the whole Naliboki Forest on the area that is a bit larger than two thousands square km.

Since 2016 the local otter population recovered in Naliboki Forest, and during the winter of 2019-2020 otters were fairly common there. It looked like there were 3-6 otters per 10 km of stretch of the main watercourses e.g. such as the rivers of Biarezina, Vusa and Volka or Shubin-Nioman canal.

However, during the winters of 2021-2022 and the beginning of the current winter (2022-2023) we faced with a low number of otters in Naliboki Forest again. The current decline in otters is not so pronounced as that we registered in the winter 2008-2009. Nevertheless, otters became not so common in this terrain with plenty of favorable habitats for this species. Along the Vol'ka river we found only two otters (big adult male and small subadult female) for about 30 km of its stretch; the Biarezina medium-sized river - 4 otters (adult female with two cubs and adult male) for 14 km of its stretch; the Zhautsianka canalized river with many beaver ponds - no otters for 16 km of its stretch; Zhouta-Nioman canal - one male otter for more that ten km of its stretch; Shubin-Nioman canal - one female otter for more that ten km of its stretch.

On the below video you may see the last otters we still have in Naliboki Forest. Mainly we took these footage in the warm season of 2022 at the Vol'ka river, Biarezina valley, Junitsa canal and Shubin-Nioman canal.